JP2669649B2 - Automotive slip control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an automobile slip control device for preventing slippage of drive wheels of a vehicle to improve running stability.

(Prior Art) Conventionally, as a slip control device for an automobile of this type, as disclosed in, for example, Japanese Patent Laid-Open No. 61-182434, a speed difference between a driving wheel and a driven wheel of the vehicle is detected, and The engine output is feedback-controlled by controlling the throttle valve opening of the engine so that the speed difference becomes a predetermined value, thereby adjusting the speed of the drive wheels to effectively prevent the slip and improve the running stability of the vehicle. The one that is designed is known.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional one, in order to prevent the slip of the driving wheels by the feedback control of the engine output, when the large slip occurs, the decrease of the engine output is slow and There is room for improvement in order to take a long time to suppress rotation and obtain quick convergence of slip.

The present invention has been made in view of such a point, and an object thereof is to reduce the engine output in a short time by adopting the feedforward control at the time of the occurrence of the slip of the driving wheels (the initial stage of the occurrence). It is an object of the present invention to speed up the convergence of the driving wheels and further improve the running stability.

In that case, if the engine output is simply feed-forward controlled to the lower side, good convergence of the drive wheels can be obtained, but at the time of starting feedback control thereafter, the engine output state is low, so There is a delay in the convergence to the target value, the return response is deteriorated, and there is a feeling that good acceleration cannot be obtained. Therefore, in the present invention, it is also an object of the present invention to reduce the engine output by feed-forward control and control it to return, thereby ensuring not only the slip convergence but also the acceleration after the slip convergence.

Further, in that case, when the engine output reduction control and the return control are controlled by the feedforward control, when the reduction target value and the recovery target value are uniquely fixed, the condition of the running road surface (paved road, snow road, etc.) ) And the vehicle speed may not be enough to control the slip. For example, on paved roads, if the driving force of the wheels is slightly reduced,
On a snowy road, the slip does not converge unless it is controlled to decrease to near zero. Further, during high-speed running, the running resistance of the vehicle is increasing, and generally, the driving torque is small at the high-speed gear stage. Therefore, in the present invention, the target value for reduction and the target value for return of the feedforward control are variably set according to the friction coefficient of the road surface and the vehicle speed.

Also, when the transmission is upshifted, inertial energy from the engine is released during switching of the power transmission path, which may cause a temporary slip in the drive wheels, but this slip ends the release of inertial energy. It will converge naturally when you do. Therefore, when the engine output is reduced and the return control is performed as in the case of a normal slip where a large driving force is applied, the degree of the output reduction is too large and the driver feels a deceleration. When a slip occurs at the time of shift-up, the reduction target value and the return target value of the feedforward control are corrected to the increasing side of the engine output.

(Means for Solving the Problems) In order to achieve the above object, the solution means of the invention according to claim 1 prevents the slip of the drive wheels by adjusting the output of the engine 1 as shown in FIG. It is assumed that the vehicle slip control device is configured as described above. Then, the output adjusting means 10 for adjusting the engine output, the slip detecting means 24, 24 'for detecting the slip of the driving wheels, and the slip detecting means 24,
A reduction control means 25 for performing feedforward control of the output adjusting means 10 so as to reduce the engine output to a set limit value when a slip detected by 24 'occurs, and the reduction control means 25.
And a return control means (26) for feed-forward controlling the output adjusting means (10) so as to return the engine output, which has undergone the reduction control by the reduction control means (25), to the set return value for a predetermined time period after the engine output reduction control by (1). further,
The setting limit value of the reduction control means 25 and the setting return value of the return control means 26 are set in advance in accordance with at least the friction coefficient of the road surface and the vehicle speed.

Further, the invention according to claim 2 includes the reduction control means 25 and the return control means 26 according to the above-described claim 1, and further includes a shift-up detecting means for detecting the shift-up time of the transmission as shown by a broken line in FIG. The output of the detection means 28, the shift-up detection means 28 and the slip detection means 24, 24 'is received, and at least when the slip of the drive wheels occurs due to the shift-up of the transmission, at least the set limit value of the reduction control means 25 is set by the engine. A configuration is provided in which a correction means 29 for correcting the output is increased.

(Operation) With the above configuration, in the inventions according to claim 1 and claim 2, when the drive wheel slips, the engine output is first feedforward controlled by the reduction control means 25 and quickly falls to the set limit value. In addition, the speed of the driving wheel is greatly reduced in a short time, and the slip is quickly converged.
Then, after that, the engine output is feedforward controlled by the return control means 26 and increases and returns to the set return value, so that the driving wheel speed can be quickly returned to the vicinity of the target value, the return response becomes good, and good acceleration is achieved. Property is obtained.

In that case, in the invention according to claim 1, since the set return value and the set return value are variably set according to the vehicle speed and the friction coefficient of the road surface, the driving force of the wheels is minimized on the paved road or at a high vehicle speed. It is controlled to reduce the acceleration to the minimum required, while it is greatly controlled to reduce slip on snowy roads and at low vehicle speeds to improve the convergence of slips, regardless of road conditions and vehicle speeds. Surely suppressed and prevented.

Further, in the invention according to claim 2, even if a temporary slip is generated due to this at the time of upshifting of the transmission, the slip is immediately converged when the release of the inertial energy of the engine is completed. At this time, if the degree of decrease in the engine output is controlled to be smaller than that when a normal slip occurs, the slip of the drive wheels is effectively suppressed and prevented without causing a feeling of deceleration.

(Effect of the Invention) As described above, according to the vehicle slip control device of the first aspect of the invention, when the slip of the drive wheel occurs, the engine output is reduced and the return control is performed by the feedforward control. The slip can be quickly converged to improve the convergence, and the recovery response of the drive wheel speed after the convergence can be improved to improve the acceleration and further improve the running stability. Can be planned. Moreover, since the engine output reduction limit value and the return value are variably set according to the friction coefficient of the road surface and the vehicle speed, optimum slip control can be executed according to the road surface condition and the vehicle speed. It is possible to achieve both.

Further, in the invention according to the second aspect, the engine output in the feedforward control is reduced when the driving wheel temporarily slips due to the shift up of the transmission while improving the convergence of the slip and the subsequent acceleration. Since the degree of is limited to a small value, it is possible to effectively prevent the drive wheels from slipping without causing a feeling of deceleration.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS.

FIG. 2 shows an overall schematic configuration of a vehicle slip control device according to the present invention, wherein 1 is an engine, and 2 is, for example, a forward 4
In the automatic transmission having one gear and one reverse gear, the engine power changed by the automatic transmission 2 is transmitted to the left and right via a propulsion shaft 3, a differential device 4 and a rear axle 5 arranged behind the transmission 2. Rear wheel
6 and 6, the rear wheel 6 is used as a drive wheel, and the left and right front wheels 7, 7
Is a driven wheel.

Further, a throttle valve 10 as an output adjusting means for adjusting an engine output by controlling an intake air amount is disposed in an intake passage 1a of the engine 1. The throttle valve 10
Is a throttle actuator that has no mechanical interlocking relationship with the accelerator pedal 11 and is composed of a step motor, etc.
The opening is electrically controlled by 12.

Further, near the front, rear, left and right wheels 6, 7, wheel speed sensors 13, 13,... For detecting the rotation speed of the wheels are provided, respectively, and an opening sensor 14, for detecting the opening of the accelerator pedal 11, Steering angle sensor 15, which detects the steering angle,
Brake sensor 16, which detects when the brake pedal is depressed,
A range sensor 17 that detects the range of the automatic transmission 2 is provided. Thus, the detection signals of the above sensors 13 to 17 are input to the controller 20 having a CPU or the like,
The controller 20 controls the engine output by controlling the opening of the throttle valve 10 so as to suppress and prevent the rear wheels (drive wheels) 6 from slipping.

Next, the slip control by the controller 20 will be described based on the control flow of FIGS.

First, as explained from the main flow of FIG. 3, after initializing the system in step S _M1 , step S _M2
Performs a shift control for setting the gear position of the automatic transmission 2 in accordance with the vehicle speed and the amount of depression of the accelerator pedal 11, and then, in step _SM3 , based on the determination flow of FIG. It is determined whether or not it has occurred. further,
In step S _M4 , the target opening NTAG of the throttle valve 10 according to the depression amount of the accelerator pedal 11 is calculated, and in step S _M5 , the slip control of the drive wheels 6 is performed based on the slip control flow of FIG. During slip control, the throttle valve 10 is controlled to the control opening STAG, and during normal control that does not require slip control, the target opening NTAG is controlled according to the pedal depression amount, and the process returns to step S _M2. Is repeated.

Next, the control flow of FIG. 4 will be described. The control flow is started by interrupting the main flow of FIG. 3 at predetermined time intervals, and at step S _I1 , the vehicle speed, the accelerator pedal opening, and the steering angle are set. After inputting various data such as data and signal processing, decrement the various control timers in step S _I2 , and turn on / off various solenoid valves of the transmission 2 to set the target gear in step S _I3. control to start the shifting, then, actually dies is controlled to the target opening NTAG or control opening STAG the opening of the throttle valve 10 in step S _I4.

Next, the shift-up spin determination flow in FIG. 5 will be described. First, in step S _U1 , shift up spin flag SUS
The value of F (S when spin occurs when shifting up the transmission)
USF = 0), and if SUSF ≠ 0, step S _U2
Then, it is determined whether or not a spin occurs (this determination is made based on whether or not a spin flag SPIN described later changes from SPIN = 255 → 0 or 100). When a spin occurs, it is further determined in step S _U3 whether or not the transmission 2 has been upshifted a predetermined time ago, and if YES, the upshift spin flag SUSF is set to SUSF = 0 in step S _U4. finish.

On the other hand, when already SUSF = 0 in step S _U1 is
In step S _U5 , it is determined whether or not the feedback control of the engine output is being performed. If the feedback control of NO is being performed, SUSF = 0 is maintained, and only when the control is shifted to the feedback control thereafter, the initial value is set to SUSF = FF Set again to and exit.

Next, the slip control flow of FIG. 6 will be described. First, it is determined in ON / OFF state of the tiger click genus switch driver of Y / N of the slip control in step S ₁ is to select, ON
When requesting a slip control state, performing slip control of the driving wheels (rear wheels) 6 at step S ₂ and subsequent.

And Thus, to determine the coefficient of friction of the extent and the road surface slip (hereinafter referred to as mu) in step S ₂ and subsequent. First, step S ₂
At rear wheel speed (drive wheel speed) WR and front wheel speed (driven wheel speed)
Compare with FW. Here, the driving wheel speed WR uses the larger speed of the left and right rear wheels, and the driven wheel speed FW uses the average of the rotational speeds of the left and right wheels. And Thus, when WR-FW is large large spin, to determine the value of (SPIN = 0 when a large spin) spin flag SPIN in step S _3, if the SPIN ≠ 0 it is determined that the time of a large spin-generating , At step S ₄ , the spin flag SPIN = 0 is set, and at step S ₅ , the road surface μ determination timer GTIM is initialized to a predetermined value (for example, GTIM = 33), and the road surface μ determination end flag GGF (μ At the end of the determination, GGF = FF) is initialized to GGF = 0, and the current driven wheel speed FW is set as the previous driven wheel speed FWOLD, and the process proceeds to step S ₁₁ .

On the other hand, if the speed difference between the front and rear wheels in step S ₂ (WR-FW) is not large, further spin flag at step S ₆ SP
To determine the value of the IN, only when a large spin SPIN = 0, a predetermined value a timer RECTM for a predetermined time measured in step S ₇ (e.g. R
Initially set to ECTM = 22). Then, SPIN = 100 spin flag SPIN in step S ₉ to determine whether the medium speed difference between the front and rear wheels (WR-FW) is at step S _8, when moderate
To, if the speed difference (WR-FW) is smaller S at Step S ₁₀
Set PIN = 255 respectively.

Thereafter, and determining the mu of the road surface in the step S ₁₁ and subsequent, first only for mu determination end flag GGF = 0 in step S ₁₁ (mu pre-determination), a timer for mu determination of the road surface in the step S ₁₂ GTIN The value of is determined and GTIN =
When a predetermined time has elapsed became 0, the follower wheel speed at this time of the driven wheel speed FW and the previous Step S ₁₃ (large spin time of occurrence)
Grasping the acceleration GG (= FW-FWOLD) of the driven wheel from the difference with FWOLD, and based on the current driven wheel speed FW and the acceleration GG of the driven wheel in step S ₁₄ , the map of the road surface from the map shown in the same step is used. Understand μ. Here, the same driven wheel speed on the map
In FW, the higher the driven wheel acceleration GG, the higher the road surface μ, so
In the region MU = 1, μ is low, in the region MU = 2, μ is medium,
In the region MU = 3, μ is high. Then, after determining the μ of the road surface is, GGF a μ determination end flag GGF in step S ₁₅ = FF
Is set to (mu determination end), and to move to the subsequent slip control step S _16.

In the slip control in step S ₁₆ and later, first to determine the presence or absence of depression of the accelerator pedal 11 in step S _16, and by performing a depression (when ON) unless slip control, the slip control flag SPINC in step S ₁₇ ( determine the value in a slip control 0), at the time of the slip control starting of SPINC ≠ 0, further to determine the value of the spin flag sPIN in step S _18, the accelerator and throttle valve opening in the spin state of convergence sPIN = 255 The process immediately proceeds to step _S36 in order to set the opening degree value according to the pedal depression amount.

On the other hand, in the case of SPIN ≠ 255 in step S _18, after setting the slip control flag SPINC to SPINC = 0 in step S _19, the rotational speed of the front and rear wheels in the feedback control of the rotational speed of the drive wheels in step S ₂₀ In order to make the difference a predetermined value ΔN according to μ of the road surface, the target rotation speed MOKU of the drive wheels is
It is preset to MOKU = FW + ΔN.

Thereafter, each spin flag SP in step S ₂₁ and S ₂₂
To determine the value and the value of the measuring timer RECTM after large spin convergence IN, at the time of a large spin generation of SPIN = 0, and to feed forward control the opening degree of the throttle valve 10 to the set limit value the routine proceeds to step S ₂₃ I do. The setting limit value of the throttle valve opening is variably set based on the setting flow of FIG. 7 in detail. In other words, in FIG. 7, the degree of the estimated μ of the running road surface is grasped in steps S _L1 and S _L2 , and according to the degree of the road surface μ, steps S _{L3 to} S _L5 are based on the map shown in each step. Then, a set limit value STAG corresponding to the rotation speed FW of the driven wheel is obtained.

Here, each map is set to have a large opening as the rotational speed FW (that is, the vehicle speed) of the driven wheel increases, and between the maps, the area MU = 3 (high μ area). The setting limit value STAG (reference value α ₃ ) is the highest, and the setting limit value STAG (reference value α ₁ ) in the region MU = 1 (low μ range) is the lowest (α ₃ > α ₂ > α ₁ ). In addition, the degree of the change in the opening degree of the set limit value STAG with respect to the increase in the vehicle speed is MU = 3 (high μ range)
Is the largest and the smallest in the region MU = 1 (low μ region) (the inclination of the characteristic line in each map is set to θ ₃ > θ ₂ > θ ₁ ). This is because it is necessary to ensure acceleration in the high μ range, and it is not so related to the vehicle speed in the low μ range.

And Thus, when a large spin occurs above, in order to change the case during spin occurs due the set limit value STAG determined from the map to the up-shifting of the transmission 2, the shift in the step S ₂₄ of FIG. 6 The value of the up spin flag SUSF is determined, and SUSF = 0 (when a spin occurs due to an upshift)
Only, predetermined times (1.2 times) the programmed limits STAG in step S ₂₅ and corrects the throttle valve opening value to large opening side.

Further, in FIG. 6 of the control flow, when the SPIN ≠ 0 large spin somewhat settled in step S _21, the timer RECT
Before the predetermined time of M ≠ 0 has elapsed, the feedforward control is performed so that the set forward limit value STAG set to the small opening value as described above is restored in a short time.
_{At 26} , the target set return value STAG corresponding to the rotational speed FW (vehicle speed) of the driven wheels is obtained based on steps S _{R1 to} S _R5 of the setting flow of FIG. The calculation of the setting return value STAG is performed in the same manner as the calculation of the setting limit value STAG in FIG. That is, each map in FIG. 8 is set to a large opening degree as the vehicle speed increases, and the area MU = 3 is set between the maps.
The set return value STAG (reference value β ₃ ) in the (high μ range) is the highest, and the set return value STAG (reference value β ₁ ) in the region MU = 1 (low μ range) is the lowest (β ₃ > β ₂ > β ₁ ). Further, the degree of the change in the opening degree of the set return value STAG is largest in the region MU = 3 (high μ region) and smallest in the region MU = 1 (low μ region) (inclination 特性₃ > ξ ₂ > of the characteristic line). ξ ₁ ).

Then, after that, the set return value obtained from the above map
And that in the case of spin occurrence due to upshifting of STAG the transmission 2 to change, to determine the value of the upshift spin flag SUSF in step S _27, when spin occurs due to SUSF = 0 (shift-up ) Only, step S ₂₈
Then, the set return value STAG is multiplied by a predetermined value (1.2 times) to correct the throttle valve opening value to the large opening side.

And Thus, SPIN in step S _21, S ₂ of the control flow of FIG. 6
When ≠ and 0 becomes timer RECTM = 0, sets the target opening value STAG1 by feedback control so that the target rotation speed MOKU of the drive wheels in step S ₂₉ (e.g., PI-PD method). In this case, the target opening value STAG1 may be reduced to near the fully closed state, and at this time the acceleration after spin convergence is impaired.Therefore, the minimum value of the target opening value STAG should be limited to the limiter value. I have. That is, calculated from the driven wheel speed FW based a limiter value STAG2 in step S ₃₀ in the same map as the step S _23, then, the target opening value STAG1 obtained from the feedback control in Step S ₃₁ compared to STAG2, towards the large value obtained in step S ₃₂ and S _33, which limits the limiter value STAG2 at a minimum.

Then, a target opening STAG in the slip control in step S _34, the target opening corresponding to the accelerator pedal depression amount
Comparing the Ntag, if the STAG ≦ Ntag are the time of the slip control required, the target opening calculated by the slip controlling the opening value TAGET to be actually controlled in step S ₃₅ STAG
And control and end.

On the other hand, if STAG> NTAG, the slip control flag SPINC is set to SPINC = 255 (when slip control is not needed) in step _S36 in order to control the opening degree according to the accelerator pedal as usual. In S ₃₇ , the μ judgment end flag GGF of the road surface is set to GGF = FF (μ judgment end), and in step S _{38 the} opening value TAGET to be actually controlled is set as the target opening NTAG according to the accelerator pedal depression amount. Control and terminate.

Therefore, in step S _2, S ₈ of the control flow of the four wheel speed sensors 13, 13 and Figure 6, constitute the slip detection unit 24 to detect the slippage of the driving wheels 6. In the control flow of FIG. 6, step S
₂₃ , the opening degree of the throttle valve 10 (output adjustment means) is set as shown in FIG. 9 (a) so that the engine output is reduced to the set limit value when the slip detected by the slip detection means 24 occurs. The lowering control means 25 is configured to perform feedforward control up to the value STAG.

Further, in step S _22, S ₂₆ of the control flow, during the lowering control after a predetermined time of the engine output by the reduction control means 25, is lowered controlled based on the throttle valve opening control of the low under the control unit 25 the engine In order to return the output to the set return value, the opening control of the throttle valve 10 is controlled to increase from the set limit value to the return opening value STAG by feedforward control as shown in FIG. Is composed. Further, in each of the maps shown in FIGS. 7 and 8, the set limit value of the drop control means 25 and the set return value of the return control means 26 correspond to the set limit value STAG of the opening degree of the throttle valve 10 and the corresponding return value. Reset value of control means 26
The configuration is set in advance by the STAG according to the μ of the road surface and the vehicle speed.

Further, in the shift-up spin determination flow of FIG. 5, in step S _U2, together constitute a slip detection means 24 'which is adapted to detect a slip of the drive wheels, in step S _U3, up-shifting of the transmission The shift-up detecting means 28 for detecting time is configured. Also,
By the step S _U4 of the judgment flow and the steps S ₂₄ , S ₂₅ , S ₂₇ , S ₂₈ of the control flow of FIG. 6, the outputs of the shift-up detection means 28 and the slip detection means 24 'are received,
When the drive wheels 6 slip due to the shift-up of the transmission 2, the throttle valve opening set limit value STAG and the set return value STAG are corrected to the larger opening side, and the set limit value and the return control of the lowering control means 25 are performed. A correcting means 29 is provided which corrects the set return value of the means 26 to an increase in the engine output.

Therefore, in the above embodiment, when a large slip with a large amount of slip occurs, the feed-forward control of the throttle valve 10 is sequentially performed by the reduction control means 25 and the return control means 26 prior to the feedback control of the throttle valve 10. As a result, the rotational speed difference between both wheels (GW-FW)
Is large as shown in FIG. 10, but at this time, as shown in FIG. 11, the opening degree of the throttle valve 10 is first lowered.
It is controlled by 25 and is rapidly reduced to the target set limit value STAG according to the rotation speed FW of the driven wheels (front wheels). As a result, the engine output is greatly reduced in a short time, the rotation speed of the drive wheels 6 is immediately reduced, and the spin is quickly converged.

Then, after that, the opening degree of the throttle valve 10 is controlled by the return control means 26, and is quickly returned to the target set return value STAG according to the rotation speed FW of the driven wheels to increase the engine output and drive. The rotation speed GW of the wheel 6 quickly returns to the vicinity of the target rotation speed MOKU in the feedback control to be performed thereafter, and this state is maintained for a predetermined time RECTM, so the return response becomes good and good acceleration is achieved. Property is obtained.

After that, since the opening of the throttle valve 10 is feedback-controlled as usual, the rotational speed GW of the drive wheel 6 is controlled.
As shown in Fig. 9 (c), the target rotational speed MOKU, which is separated from the driven wheel speed FW by a predetermined speed, is favorably converged, and the subsequent slip is effectively prevented.

Here, the set control value STAG in the feed-forward control of the throttle valve opening by the reduction control means 25 and the set return value STAG by the return control means 26 are the vehicle speed and the road surface, respectively, as shown in FIG. 7 and FIG. When the vehicle is running at low vehicle speeds or on low μ roads, the throttle valve opening is adjusted to near the fully closed position and the engine output is greatly reduced so that slip is effectively suppressed and prevented. it can.

Further, when the driving wheel 6 temporarily slips due to the upshifting of the transmission 2, the situation immediately converges after the inertia energy of the engine 1 is released. When the engine output is controlled to decrease greatly as usual, A sense of deceleration occurs, but during this slip, the set limit value of the drop control means 25
Since both the STAG and the set return value STAG of the return control means 26 are corrected to the large opening side by the correction means 29 and the engine output reduction control is stopped small, drive wheel slip is effectively suppressed without causing a feeling of deceleration. , Can be prevented.

In the above-described embodiment, when the transmission 2 slips up, the throttle valve opening setting limit value STAG and the set return value STAG are corrected to the large opening side by the feedforward control. At least the set limit value STAG may be corrected based on the relationship with the engine inertia energy release time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 9 show an embodiment of the present invention, FIG. 2 is an overall schematic configuration diagram, and FIGS. 3 to 8 are flow charts showing slip control of driving wheels by a controller, respectively.
Fig. 10 is an explanatory diagram showing control for decreasing and returning the engine output by feedforward control, and control of the opening of the throttle valve by feedback control. Fig. 10 shows how the rotational speeds of the driving wheels and the driven wheels during a large slip change. FIG. 11 is an operation explanatory diagram showing how the throttle valve opening changes during a large slip. 1 ... engine, 6 ... rear wheel (drive wheel), 7 ... front wheel (driven wheel), 10 ... throttle valve (output adjustment means), 13
…… wheel speed sensor, 20 …… controller, 24, 24 '…
… Slip detection means, 25 …… Lower control means, 26 …… Return control means, 28 …… Shift up detection means, 29 …… Correction means.

Claims (2)

(57) [Claims] 1. A slip control device for an automobile, wherein an output of an engine is adjusted to prevent a slip of a driving wheel, the output control means adjusting an engine output, and a slip detection for detecting a slip of the driving wheel. Means, a decrease control means for feed-forward controlling the output adjustment means so as to reduce the engine output to a set limit value when a slip detected by the slip detection means occurs, and a predetermined time after the decrease control of the engine output by the decrease control means In the meantime, there is provided a return control means for performing feed-forward control of the output adjusting means so as to return the engine output that has been lowered controlled by the reduction control means to the set value restoration, and the setting limit value of the reduction control means and the return control means The set return value is preset according to the friction coefficient of the road surface and the vehicle speed at least. Car of the slip control system. 2. A slip control device for an automobile, wherein an output of an engine is adjusted to prevent a slip of a driving wheel, wherein an output adjusting means for adjusting an engine output and a slip detection for detecting a slip of the driving wheel. Means, a decrease control means for feed-forward controlling the output adjustment means so as to reduce the engine output to a set limit value when a slip detected by the slip detection means occurs, and a predetermined time after the decrease control of the engine output by the decrease control means In addition, a return control means for feed-forward controlling the output adjusting means so as to return the engine output controlled by the reduction control means to the set return value, and a shift-up detection for detecting a shift-up of the transmission. Receiving the output of the shift-up detecting means and the slip detecting means, and When a slip occurs in the driving wheels caused by Futoappu, at least vehicle slip control system being characterized in that a correcting means for correcting the set limit values of the reduction control means increasing side of the engine output.